This invention relates to a gas-fired artificial log assembly for a fireplace, and more particularly to a gas log assembly which provides a flame that closely simulates visually the burning of logs including realistic flame colors and also results in a reduction in the amount of carbon monoxide generated.
Gas burning fireplaces almost invariably have some sort of artificial logs so as to simulate the burning of logs and the appearance of an actual wood burning fireplace. Artificial logs formed from a refractory material such as ceramic fibers are known and have been used for some time. When heated to temperatures above approximately 1470xc2x0 F., such logs have a visible glow simulating the appearance of an actual burning wood log.
There has been a substantial amount of effort in the prior art directed toward artificial log assemblies known as log sets, which produce the visible effects of burning logs including the red, blue and yellow colorations as the burning gas creates a flame that dances and jumps against the artificial logs. Examples of such log sets are illustrated in U.S. Pat. Nos. 5,069,200 and 5,388,566. It is therefore readily seen that efforts have been made in the prior art toward improving the output of gas log sets so that visually the logs appear as actual burning logs and the flames appear to be realistic of such burning logs.
One of the problems for which the prior art has not provided a complete solution is that of reducing the undesirable products of combustion resulting from the incomplete combustion of the gas such as, for example, carbon monoxide. This is particularly important where the log sets are used in unvented fireplaces which have oxygen depletion safety features that shut off the flow of fuel when the oxygen level in the environment of the fireplace drops below a certain value, such as for example, 18 percent.
Consequently, it is a primary object of the present invention to provide a gas burner log set which provides a visually realistic burning flame and glow on at least one of the logs while reducing carbon monoxide and eliminating sooting problems.
It is another object of the present invention to provide a gas burner log set including at least a pair of ceramic fiber logs in which the gas to air ratio is optimized to produce a pronounced glow of the ceramic fiber log surface and a low amount of carbon monoxide.
It is a further object of the present invention to provide a gas burner log set having at least two ceramic fiber logs with a gas burner therebetween, the front one of the logs having a substantially smooth planar rear surface on at least a portion thereof inclined angularly relatively toward the front surface of the rear of the logs to provide an elongated substantially triangular flame guide channel, the burner outlet ports being directed to provide the flow of gas toward the front surface of the rear of the logs and there being an air gap between the burner and the rear surface of the front one of the logs.
Accordingly, the present invention provides a log set for a gas burning fireplace which includes a pair of spaced apart ceramic fiber logs having a gas burner disposed between the logs and directing gas and thus the flame toward the front surface of the rear of the logs, at least a portion of the rear surface of the front of the logs being a substantially smooth planar ramp angularly inclined upwardly toward the front rough textured surface of the rear log to form an elongated substantially triangular flame channel with an apex at the top which directs the flame onto the front surface of the rear log, and spaced from the burner to form an air space therebetween. The air space between the burner and the rear angular surface of the front log is selected to provide blue flames that burn clean, hotter and with increased intensity against the front surface of the rear log as the velocity of the flame increases as it moves upwardly toward the apex of the flame channel. With this construction, the gas/air ratio may be optimized to produce a pronounced glow of the ceramic fiber rear log front surface simulating a highly desirable glowing coal effect. Even distribution of mixing air is maintained between the smooth planar ramp surface and the burner ports thereby resulting in improved combustion and elimination of sooting problems.